With the SmartWool Mid 250 Zip T, you quit only when you want to. With next-to-skin Merino, it wicks and regulates core temp as a solo piece or smartly layers up when it gets chilly. First Layer fit with no-chafe. Features: 10" center front zipper Flatlock seam construction designed to eliminate chafing Form Fit Interlock knit UPF 50 Shoulder panels eliminate top shoulder seams Machine washable Fabric: 100% Merino Wool